The redshift of this galaxy reaches 9.51 meaning that it was seen when the age of the universe was only 550 million years old. The rate of star formation in it is 10 times greater than the Milky Way
An international group of scientists, including Prof. Adi Tzitrin from Ben Gurion University, reports in an article published in the journal Science yesterday about the discovery of a compact galaxy that was enlarged through gravitational collapse. The galaxy is characterized by strong emission lines at a redshift of 9.51.
Using first-of-its-kind observations from the James Webb Space Telescope, a team led by researchers from the University of Minnesota (which also includes Prof. Adi Tzitrin of Ben-Gurion University) looked more than 13 billion years into the past to discover a unique, tiny galaxy that was forming new stars at an extremely high rate for its size .
The galaxy in question has a redshift of 9.51. This means that the light we see from it was emitted when the universe was only about 550 million years old, or about 4% of its current age. This makes the galaxy one of the most distant and oldest objects ever observed by astronomers. The high redshift value also indicates that the galaxy is moving away from us at a very high speed due to the expansion of the universe.
The galaxy is one of the smallest ever discovered at this distance – about 500 million years after the Big Bang – and may help astronomers learn more about galaxies that existed shortly after the universe began.
The article was published on April 13, 2023 ב-Science
“This galaxy is far beyond the reach of all telescopes except James Webb, and the first observations of its kind of the distant galaxy are spectacular,” said Patrick Kelly, senior author of the paper and a professor in the School of Physics and Astronomy at the University of Minnesota. “We have never looked at galaxies when the universe was so young at such a level of detail. The volume of the galaxy is about one millionth that of the Milky Way, but we can see that it still creates the same number of stars every year.”
The James Webb Telescope can view a field wide enough to image an entire galaxy cluster at once. The researchers were able to find and study this tiny new galaxy thanks to a phenomenon called gravitational bending – in which mass, such as that in a galaxy or cluster of galaxies, bends and magnifies light. Galaxy cluster lensing made this small background galaxy appear 20 times brighter than it would have if the cluster hadn’t boosted its light.
The researchers then used spectroscopy using the ALMA telescope in Chile to measure how far away the galaxy was, in addition to some of its physical and chemical properties. Studying galaxies that existed when the universe was much younger could help scientists get closer to answering a huge question in astronomy about how the universe became re-ionized.
“The galaxies that existed when the universe was in its infancy are very different from what we see in the nearby universe now,” explained Haley Williams, first author of the paper and a doctoral student at the Minnesota Institute for Astrophysics. “This discovery can help us learn more about the characteristics of those first galaxies, how they differ from galaxies close to us, and how the earlier galaxies were formed.”
The James Webb Telescope can collect about 10 times more light than the Hubble Space Telescope and is much more sensitive at red and longer wavelengths in the infrared spectrum. This allows scientists to access an entirely new window of data, the researchers said.
The strong nebular emission lines indicate that the galaxy is undergoing intense star formation, suggesting that it is a prime candidate for studying the early stages of galaxy formation and evolution in the early universe. The discovery provides new insights into the formation and evolution of galaxies in the early universe, and sheds light on the properties of the universe during the cosmic dawn.
Redshift is a measure of the expansion of the universe, and it indicates how much the wavelength of the light emitted by a distant object is stretched during its journey through space. A higher value of redshift indicates that the object is further away and that the light is stretched more.
Its redshift of 9.51 means that the light we see from it was emitted when the universe was only about 550 million years old, or about 4% of its current age. This makes the galaxy one of the most distant and oldest objects ever observed by astronomers. The high redshift value also indicates that the galaxy is moving away from us at a very high speed due to the expansion of the universe.
Compact size: the galaxy is very small and compact, and its diameter is estimated to be about one-tenth that of the Milky Way.
Strong emission lines: The galaxy shows strong emission lines in its spectrum, produced by the ionized gas surrounding the young stars in the galaxy. These emission lines provide information about the galaxy’s properties, such as its star formation rate and gas composition.
Intense star formation: The presence of strong emission lines indicates that the galaxy is undergoing intense star formation, with the rate of star formation estimated to be about 10 times that of the Milky Way.
Young age: The intense star formation and compact size of the galaxy indicate that it is in the early stages of its formation and development.
The James Webb Space Telescope has an incredible ability to see very far into the universe,” said Williams. “This is one of the most exciting things about this article. We see things that previous telescopes were only ever able to capture. It’s actually getting a snapshot of our universe in the first 500 million years of its life.”
The research was supported by the National Science Foundation and NASA through the Space Telescope Science Institute, and with additional funding from the United States-Israel Binational Science Foundation and the State Research Agency of Spain.
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